Peripheral nervous system communicates with vast network that transmits information from brain to spinal cord to various parts of the body. These nerves send sensory information back to brain and spinal cord. Damage to the nervous system interferes with various vital connections and leads to peripheral neuropathy. Mononeuropathies involves damage to a single nerve whereas polyneuropathy is caused by multiple nerves being affected. When two or more nerves in the separate areas of the body are affected, the condition is known as mononeuritis multiplex. There are around 100 types of peripheral neuropathy with different characteristic set of symptoms, development and causes.
Causes of peripheral neuropathy
- Diabetes mellitus, Chronic renal failure, porphyria, amyloidosis, liver failure, hypothyroidism
- Auto immune disease like rheumatoid arthritis or Guillain-Barre syndrome, systemic lupus erythematosis, leprosy, Sjögren's syndrome
- Post herpetic neuralgia
- AIDS, syphilis
- Vitamin B12 ,Vitamin A, Vitamin E, Vitamin B1 (Thiamin) and folate deficiency
- Inherited disorders like amyloid polyneuropathy or Charcot-Marie-Tooth disease, Friedreich's ataxia
- Exposure to toxins and heavy metals like gold compounds, lead, arsenic, mercury, and organophosphate pesticides
- Cancer therapy drugs like vincristine (Oncovin, Vincasar), and other medications and antibiotics such as metronidazole (Flagyl), and isoniazid (Nydrazid, Laniazid)
- Physical injury (trauma) like compression, pinching, cutting, projectile injuries (i.e. gunshot wound),strokes including prolonged occlusion of blood flow
- Kidney disorders
- Hormonal imbalances
- Vascular damage and blood diseases
- Repetitive stress
Signs and symptoms of peripheral neuropathy
Signs and symptoms are related to the type of affected nerve which may be seen over the period of time.
- Numbness, tremor, and gait imbalance due to loss of function
- Tingling, pain, itching,
- Pain in the muscles (myalgia), cramps,
- Sensory loss
- Proximal weakness
- Focal sensory disturbance or weakness
- Loss of reflexes
- Damage of sensory fibers lessens the ability to feel and touch.
Diagnosis of peripheral neuropathy
The diagnosis is usually difficult because of the variable symptoms. Primarily a general physical examination is needed.
- A blood test is done to detect diabetes vitamin deficiencies, liver or kidney dysfunction, other metabolic disorders and signs of abnormal immune system activity
- Cerebrospinal fluid examination can reveal about the abnormal antibiotics associated with neuropathy.
- Muscle strength indicates motor fiber involvement.
- Sensory damage can be detected by testing the patient's ability to register vibrations, light touch, body position and temperature.
- CT scans can detect bone and vascular irregularities.
- X-rays are passed to body at various angles and are detected by a computerized scanner.
- MRI scan can indicate muscle quality and size and to determine fatty replacement of muscle and sustained compression damage of nerve fiber.
- Electromyography (EMG) involves inserting a fine needle into the muscle to compare the amount of electrical activity when the muscles are at rest and contraction.
- Nerve conduction velocity (NCV) tests determine measure the degree of damage in larger nerve fibers.
- Nerve biopsy examines a sample of nerve tissue from the lower leg.
- Skin biopsy is done by removing the thin skin sample to reveal the damage found in the smaller fibers
Treatment for Peripheral Neuropathy
Primarily any underlying condition is treated followed by the systematic treatment. Control of blood glucose levels, maintaining an optimal weight, eating a balanced diet. Avoiding alcohol consumption can greatly help to reduce this disease. Usage of Immunosuppressive drugs such as prednisone, cyclosporine, or azathioprine may be beneficial.
Drugs which have proved useful to treat peripheral neuropathy are mexiletine (used to correct heart beat), antiepileptic drugs, antidepressants and anesthetics to relieve more intractable pain.
Orthopedic shoes are used to improve gait disturbances and help prevent foot injuries. Surgical intervention gives immediate relief from mononeuropathies caused due to compression or entrapment injuries. Malignant tumor removal can alleviate the damaging pressure on the nerves. Other treatments like TENS (Transcutaneous Electrical Nerve Stimulation) can also be used.